Method and structure for forming FinFET CMOS with dual doped STI regions

ABSTRACT

A method of making a semiconductor device includes forming a first fin of a first transistor in a substrate; forming a second fin of a second transistor in the substrate; disposing a first doped oxide layer including a first dopant onto the first fin and the second fin, the first dopant being an n-type dopant or a p-type dopant; disposing a mask over the first fin and removing the first doped oxide layer from the second fin; removing the mask and disposing a second doped oxide layer onto the first doped oxide layer over the first doped oxide layer covering the first fin and directly onto the second fin, the second doped oxide layer including an n-type dopant or a p-type dopant that is different than the first dopant; and annealing to drive in the first dopant into a portion of the first fin and the second dopant into a portion of the second fin.

DOMESTIC PRIORITY

This application is a continuation of U.S. patent application Ser. No.14/834,789, filed Aug. 25, 2015, the disclosure of which is incorporatedby reference herein in its entirety.

BACKGROUND

The present invention relates to metal-oxide-semiconductor field-effecttransistors (MOSFET), and more specifically, to fin-type field-effecttransistors (FinFET).

The MOSFET is a transistor used for amplifying or switching electronicsignals. The MOSFET has a source, a drain, and a metal oxide gateelectrode. The metal gate is electrically insulated from the mainsemiconductor n-channel or p-channel by a thin layer of insulatingmaterial, for example, silicon dioxide or glass, which makes the inputresistance of the MOSFET relatively high. The gate voltage controlswhether the path from drain to source is an open circuit (“off”) or aresistive path (“on”).

N-type field effect transistors (NFET) and p-type field effecttransistors (PFET) are two types of complementary MOSFETs. The NFET useselectrons as the current carriers and with n-doped source and drainjunctions. The PFET uses holes as the current carriers and with p-dopedsource and drain junctions.

The FinFET is a type of MOSFET. The FinFET is a double-gate ormultiple-gate MOSFET device that mitigates the effects of short channelsand reduces drain-induced barrier lowering. The “fin” refers to thenarrow channel between source and drain regions. A thin dielectric layeron either side of the fin separates the fin channel from the gate.

SUMMARY

According to an embodiment, a method of making a semiconductor deviceincludes forming a first fin of a first transistor in a substrate;forming a second fin of a second transistor in the substrate; disposinga first doped oxide layer including a first dopant onto the first finand the second fin, the first dopant being an n-type dopant or a p-typedopant; disposing a mask over the first fin and removing the first dopedoxide layer from the second fin; removing the mask and disposing asecond doped oxide layer onto the first doped oxide layer over the firstdoped oxide layer covering the first fin and directly onto the secondfin, the second doped oxide layer including an n-type dopant or a p-typedopant that is different than the first dopant; and annealing to drivein the first dopant into a portion of the first fin and the seconddopant into a portion of the second fin.

According to another embodiment, a method of making a semiconductordevice includes forming a first fin of a first transistor in asubstrate; forming a second fin of a second transistor in the substrate;disposing a first doped oxide layer including a first dopant onto thefirst fin and the second fin, the first dopant being an n-type dopant ora p-type dopant; disposing a mask over the first fin and removing thefirst doped oxide layer from the second fin; removing the mask anddisposing a second doped oxide layer onto the first doped oxide layerover the first fin and directly onto the second fin, the second dopedoxide layer including an n-type dopant or a p-type dopant that isdifferent than the first dopant; recessing the first doped oxide and thesecond doped oxide to form a first doped oxide spacer along a sidewallof the first fin and a second doped oxide spacer along a sidewall of thesecond fin; and annealing to drive in the first dopant into a portion ofthe first fin and the second dopant into a portion of the second fin.

Yet, according to another embodiment, a semiconductor device includes afirst transistor including a first fin patterned in a substrate, thefirst fin including a first doped region including a first dopant, thefirst dopant being an n-type dopant or a p-type dopant; a first dopedoxide spacer disposed along a portion of a sidewall of the first finadjacent to the first doped region and including the first dopant; asecond doped oxide spacer disposed over the first doped oxide spacer andincluding a second dopant, the second dopant being different than thefirst dopant; a second transistor including a second fin patterned inthe substrate, the second fin including a second doped region includingthe second dopant; and a third doped oxide spacer disposed along aportion of a sidewall of the second fin adjacent to the second dopedregion of the second fin and including the second dopant.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The forgoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIGS. 1A-8 illustrate an exemplary method of making a semiconductordevice according to a first embodiment of the present invention, inwhich:

FIG. 1A is a cross-sectional side view of NFET (first transistor) andPFET (second transistor) fins patterned in a substrate;

FIG. 1B is a cross-sectional side view after forming dielectric spacersalong fin sidewalls;

FIG. 1C is a cross-sectional side view after etching back the substratearound the fins;

FIG. 2 is a cross-sectional side view after depositing a conformal layerof a p-doped oxide (first doped oxide) over the fins;

FIG. 3 is a cross-sectional side view after covering the NFET with amask and removing the p-doped oxide (oxide doped with p-type dopants)from around the PFET fins;

FIG. 4 is a cross-sectional side view after removing the mask anddepositing a conformal layer of n-doped oxide (second doped oxide dopedwith n-type dopants) over the fins;

FIG. 5 is a cross-sectional side view after annealing to drive thedopants into the fins and the substrate;

FIG. 6 is a cross-sectional side view after etching to recess thep-doped oxide and the n-doped oxide and leave spacers around a portionof the fins;

FIG. 7A is a cross-sectional side view after depositing an undoped oxidearound the fins;

FIG. 7B is a cross-sectional side view after recessing the undoped oxideand removing the spacers and hard mask to expose the fin channels;

FIG. 8 is a cross-sectional side view after forming gates over the finchannels;

FIGS. 9-11 illustrate an exemplary method of making a semiconductordevice according to a second embodiment of the present invention, inwhich:

FIG. 9 is a cross-sectional side view after etching to remove then-doped oxide and the p-doped oxide from the fins of FIG. 5;

FIG. 10 is a cross-sectional side view after depositing an undoped oxidearound the fins, recessing the undoped oxide, and removing the spacersand hard mask;

FIG. 11 is a cross-sectional side view after forming gates around thefin channels;

FIGS. 12-15 illustrate an exemplary method of making a semiconductordevice according to a third embodiment of the present invention, inwhich:

FIG. 12 is a cross-sectional side view after etching to recess thep-doped oxide and the n-doped oxide and leave spacers around a portionof fins of FIG. 4;

FIG. 13 is a cross-sectional side view after annealing to drive in thedopants into the fins and the substrate;

FIG. 14 is a cross-sectional side view after removing the spacers andhard mask and depositing an undoped oxide around the fins; and

FIG. 15 is a cross-sectional side view after forming gates over the finchannels.

DETAILED DESCRIPTION

Bulk FinFET transistors may have various drawbacks. For example,punchthrough stop (PTS) doping (substrate doping) may be necessary underthe fin channel region to prevent source/drain punch-through. Alignmentof the gate, shallow trench isolation (STI) regions, and PTS dopingregions is challenging, despite being an important feature. A highaspect ratio fin structure also may pose challenges for patterning.

Accordingly, embodiments of the present invention provide methods ofmaking semiconductor devices with a dual doped STI liner. The methodsonly need a single mask for patterning. The methods do not includeetching materials through the entire depth of high aspect ratio STIs.The methods also do not include depositing a capping layer onto thedoped oxide. Embodiments of the inventive structure and methods aresuitable for highly scaled fin pitch devices. Like reference numeralsrefer to like elements across different embodiments.

The following definitions and abbreviations are to be used for theinterpretation of the claims and the specification. As used herein, theterms “comprises,” “comprising,” “includes,” “including,” “has,”“having,” “contains” or “containing,” or any other variation thereof,are intended to cover a non-exclusive inclusion. For example, acomposition, a mixture, process, method, article, or apparatus thatcomprises a list of elements is not necessarily limited to only thoseelements but can include other elements not expressly listed or inherentto such composition, mixture, process, method, article, or apparatus.

As used herein, the articles “a” and “an” preceding an element orcomponent are intended to be nonrestrictive regarding the number ofinstances (i.e. occurrences) of the element or component. Therefore, “a”or “an” should be read to include one or at least one, and the singularword form of the element or component also includes the plural unlessthe number is obviously meant to be singular.

As used herein, the terms “invention” or “present invention” arenon-limiting terms and not intended to refer to any single aspect of theparticular invention but encompass all possible aspects as described inthe specification and the claims.

As used herein, the term “about” modifying the quantity of aningredient, component, or reactant of the invention employed refers tovariation in the numerical quantity that can occur, for example, throughtypical measuring and liquid handling procedures used for makingconcentrates or solutions. Furthermore, variation can occur frominadvertent error in measuring procedures, differences in themanufacture, source, or purity of the ingredients employed to make thecompositions or carry out the methods, and the like. In one aspect, theterm “about” means within 10% of the reported numerical value. Inanother aspect, the term “about” means within 5% of the reportednumerical value. Yet, in another aspect, the term “about” means within10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% of the reported numerical value.

Turning now to the Figures, FIGS. 1A-8 illustrate an exemplary method ofmaking a semiconductor device according to a first embodiment. FIG. 1Ais a cross-sectional side view of NFET 121 (first transistor) and PFET122 (second transistor) fins 110 patterned in a substrate 101. In otherembodiments, the NFET 121 is a first transistor, and the PFET 122 is asecond transistor. The first and second transistors are differenttransistors. The fins 110 within each transistor (NFET 121 and PFET 122)are arranged in a fin array. Each first and second transistor includesone fin, two fins, or an array of fins.

Non-limiting examples of suitable substrate 101 materials includesilicon, sapphire, germanium, gallium arsenide, silicon germanium,indium arsenide, indium phosphide, or any combination thereof. In someembodiments, the substrate 101 material of the NFET 121 is the same ordifferent than the substrate material of the PFET 122. In otherembodiments, the substrate 101 material forming the fins 110 in the NFET121 is silicon, and the substrate 101 material forming the fins 110 inthe PFET 122 is silicon germanium.

The thickness of the substrate 101 is not intended to be limited. In oneaspect, the thickness of the substrate 101 is in a range from about 0.3millimeters (mm) to about 1.5 mm. In another aspect, the thickness ofthe substrate 101 is in a range from about 0.5 mm to about 0.75 mm.

The fins 110 may be formed in the substrate 101 by depositing a hardmask 111 material over a bulk substrate 101. Non-limiting examples ofsuitable materials for the hard mask 111 include silicon oxide, siliconnitride, or any combination thereof. The fins 110 are patterned in theNFET 121 and PFET 122 regions by, for example, sidewall imagingtransfer.

In some aspects, the fins 110 have a height 112 in a range from about 20nanometers (nm) to about 100 nm and a width 113 in a range from about 4nm to about 30 nm. In other aspects, the fins 110 have a height 112 in arange from about 25 nm to about 50 nm and a width 113 in a range fromabout 6 nm to about 10 nm.

The thickness of the hard mask 111 over the fins 110 may generally varyand is not intended to be limited. In some aspects, the thickness of thehard mask 111 is in a range from about 10 nm to about 100 nm. In otheraspects, the thickness of the hard mask 111 over the fins 110 is in arange from about 25 nm to about 50 nm.

FIG. 1B is a cross-sectional side view after forming spacers 130 alongfin 110 sidewalls. Non-limiting examples of suitable materials for thespacers 130 include dielectric materials, for example, dielectric oxides(e.g., silicon oxide), dielectric nitrides (e.g., silicon nitride),dielectric oxynitrides, or any combination thereof. The spacer 130material is deposited by a deposition process, for example, chemicalvapor deposition (CVD) or physical vapor deposition (PVD). The spacer130 material may be etched by a dry etch process, for example, areactive ion etching (RIE) process.

The thickness of the spacers 130 may generally vary and is not intendedto be limited. In some aspects, the thickness of the spacers 130 is in arange from about 2 nm to about 15 nm. In other aspects, the thickness ofthe spacers 130 is in a range from about 4 nm to about 8 nm.

FIG. 1C is a cross-sectional side view after removing a portion of thesubstrate 101 material around the fins 110. The etching process employedmay be a dry etching process, for example, an RIE process. The substrate110 is etched to leave a gap region 140 between the spacers 130 and thesubstrate 101. The fins 110 may be etched to have sidewalls that aresubstantially parallel or tapered. Or the fins 110 may be etched to bewider or narrower in the gap region 140 compared to the region 141 linedby the spacers 130.

FIG. 2 is a cross-sectional side view after depositing a conformal layerof a p-doped oxide 210 (first doped oxide) over the fins 110 of the NFET121 (first transistor) and the PFET 122 (second transistor). The p-dopedoxide 210 includes an oxide material that is doped with a p-type dopant(e.g., boron) (first dopant). Non-limiting examples of suitable oxidesinclude but are not limited to, silicon dioxide, spin-on-glass, aflowable oxide, a high density plasma oxide, or any combination thereof.

In some embodiments, the first dopant is an n-type dopant, which dependson the type of transistor. The n-doped oxide may include phosphorusdoped oxide or arsenic doped oxide. The p-doped oxide 210 may includeboron doped oxide. In other embodiments, p-doped oxide 210 may be anydoped oxide, which depends on the type(s) of transistors.

The p-doped oxide 210 (first doped oxide) forms gaps in regions 211between the fins 110. The regions 211 are voids that form when thedistance 220 between the fins 110 is large enough. To form the regions211, the thickness of the p-doped oxide 210 layer is greater than halfthe distance 220 between the fins 110. For a 7 nm node, for example, thedistance 220 is about 20 nm, with the fin 110 pitch being about 27 nmand the fin width being about 7 nm). A 10 nm thick layer of the p-dopedoxide 210 will then pinch off to form the voids in region 211.

The p-doped oxide 210 may be formed by a suitable deposition process.Non-limiting examples of suitable deposition methods include chemicalvapor deposition (CVD), atomic layer deposition (ALD), plasma enhancedCVD (PECVD), low pressure CVD (LPCVD), or any other suitable depositiontechniques.

In some embodiments, the distance 220 between the fins 110 is in a rangefrom about 10 nm and about 100 nm. In other embodiments, the distance220 between the fins 110 is in a range from about 15 nm to about 30 nm.

In some embodiments, the thickness of the p-doped oxide 210 is in arange from about 3 nm to about 30 nm. In other embodiments, thethickness of the p-doped oxide 210 is in a range from about 5 nm toabout 15 nm.

FIG. 3 is a cross-sectional side view after covering the NFET 121 regionwith a mask 301 and removing the p-doped oxide 210 from around the PFET122 fins 110. Lithography or any other suitable patterning technique canbe used to form the mask 301. The mask 301 may be, for example, anorganic planarizing layer (OPL) resist. The mask 301 protects the NFET121 region (first transistor).

Initially, the thicker portion of the p-doped oxide 210 is recessed inthe region 140 beneath the spacers 130. The p-doped oxide 210 may berecessed by performing a dry etching process, for example, an RIEprocess. The dry etching process is employed to recess the p-doped oxide210 by an amount in a range from about 15 to about 60 nm, or by anamount in a range from about 30 to about 40 nm.

An isotropic etching process, for example, a wet etch process containinghydrofluoric acid, is then employed to remove the thinner portion of thep-doped oxide layer in the region 141 over the spacers 130.

FIG. 4 is a cross-sectional side view after removing the mask 301 anddepositing a conformal layer of n-doped oxide 410 (second doped oxide)over the fins 110. The mask 301 may be stripped away by ashing.

The n-doped oxide 410 (second doped oxide) is deposited over the p-dopedoxide 210 (first doped oxide) over the NFET 121 (first transistor) anddirectly onto the fins 110 of the PFET 122 (second transistor). Thelayer of the p-doped oxide 210 over the NFET 121 acts as a mask toprotect the NFET 121, which means that the n-doped oxide 410 does notneed to be removed from the NFET 121 region. A second mask is notrequired to form transistors that are doped with different dopants.

The n-doped oxide 410 (second doped oxide) includes an oxide materialthat is doped with an n-type dopant (e.g., phosphorus or arsenic)(second dopant). In some embodiments, the second dopant of second dopedoxide is an n-type dopant or a p-type dopant that is different than thefirst dopant of the first doped oxide. The p-doped oxide 210 may bephosphorus doped oxide. In other embodiments, n-doped oxide 410 may beany doped oxide, which depends on the type(s) of transistors.

The n-doped oxide 410 (second doped oxide) forms gaps in the region 411between the fins 110. The regions 411 are voids that naturally form whenthe distance 220 between the fins 110 is large enough, as describedabove for the regions 211 in FIG. 2. The n-doped oxide 410 may be formedas described above for the p-doped oxide 210 also in FIG. 2.

In one embodiment, the NFET 121 (first transistor) includes a first fin110, and the PFET 122 (second transistor) includes a second fin 110. TheNFET 121 or the PFET 122 includes a third fin 110 adjacent to the firstor second fin 110, and the first doped oxide layer 210 or the seconddoped oxide layer 410 pinches off between the third fin 110 and eitherthe first or second fin 110.

FIG. 5 is a cross-sectional side view after annealing to drive thedopants into the fins 110 and the substrate 101. A thermal annealingprocess drives the p-type dopants and the n-type dopants of the p-dopedoxide 210 and the n-doped oxide 410, respectively, into the exposed finregions to form doped fin regions 501, 502. The dopants diffuse at leasta few nanometers into the fins 110 to form the doped fin regions 501,502. The dopants are also driven into the substrate 101 to formcorresponding doped substrate regions 503, 504. The doped fin regions501, 502 and doped substrate regions 503, 504 form the punchthroughstopping (PTS) regions.

In the NFET 121, the doped fin regions 501 and doped substrate regions503 will be doped with the type of dopant within the overlaying dopedoxide layer. For example, the p-type dopants from the p-doped oxide 210will be driven into fins 110 and substrate 101 of the NFET 121. As longas the p-doped oxide 210 is thick enough to block the n-type dopantsfrom the overlaying n-doped oxide 410, no cross doping from the n-dopedoxide 410 will occur. The n-type dopants from the n-doped oxide 410 willbe driven into the fins 110 and substrate 101 of the PFET 122. The dopedsubstrate regions 503, 504 include a gradient dopant profile.

The fin channels 510 are protected by the spacers 130 and remainundoped. The spacers 130 function as a diffusion barrier in the region141 of the fins 110. Thus, the dopants are only driven into the fins 110in the region 140 not protected by the spacers 130.

In another embodiment (not shown), the annealing to drive in the dopantsmay be performed after depositing an undoped oxide around and betweenthe fins 110 (see FIG. 7A).

FIG. 6 is a cross-sectional side view after etching to recess thep-doped oxide 210 and the n-doped oxide 410 and leave spacers 601, 602,and 603 around the fins 110. The spacers 601, 602, and 603 line the fin110 sidewalls in the region between the spacer 130 and the dopedsubstrate regions 503 and 504. A directional etching process, forexample, an RIE process is performed to form the spacers 601, 602, and603. The thickness of the spacers 601, 602, and 603 is partially definedby the thickness of the spacers 130.

Two types of spacers form in the NFET 121 (first transistor) region.Spacer 601 is a double layer (bilayer) spacer including two dopedoxides, p-doped oxide 210 and n-doped oxide 410. Spacer 601 forms alongouter sidewalls (one portion) of the outermost fins 610 in the array offins. The single layer spacer 602, which includes the p-doped oxide 210lines the remaining fin 110 sidewalls (along another portion). Anadvantage of using methods that form the double layer spacer 601 is thatonly one mask (mask 301 in FIG. 3) must be used to form different dopedfin regions 501, 502 and substrate doped regions 503, 504 as shown inFIG. 5. The first doped oxide layer (p-doped oxide 210) functions as aprotective mask over the first transistor (NFET 121), as shown in FIG.4.

One type of spacer forms in the PFET region 122 (second transistor)region. Spacer 603 is a single layer spacer, which includes the n-dopedoxide 410.

FIG. 7A is a cross-sectional side view after depositing an undoped oxide701 around the fins 110, which will form the STI regions between thefins 110. The undoped oxide 701 may be a low-k dielectric oxide,including but not limited to, spin-on-glass, a flowable oxide, a highdensity plasma oxide, or any combination thereof. The undoped oxide 701is deposited by a suitable deposition process, including, but notlimited to CVD, PVD, plasma enhanced CVD, atomic layer deposition (ALD),evaporation, chemical solution deposition, or like processes. Aplanarization process, for example, chemical mechanical planarization(CMP), is performed to smooth the surface of updoped oxide 701.

FIG. 7B is a cross-sectional side view after recessing the undoped oxide701 and removing the spacers 130 and hard mask 711 to expose the finchannels 510. The undoped oxide 701 is recessed by an etching process,for example, by oxide ME. The spacers 130 are stripped by, for example,a hot phosphoric acid etch if the spacers and the caps are siliconnitride. The undoped oxide 701 is recessed to a region that is below theinterface 710 between the doped fin regions 501, 502 and the finchannels 510.

FIG. 8 is a cross-sectional side view after forming gates 810, 811 overthe fin channels 510. The gate stacks of the gates 810, 811 are high-kmetal gates formed, for example, by depositing one or more high-kdielectric materials, one or more workfunction metals next to high-kdielectric materials, and one or more metal gate conductor materials.The high-k dielectric material(s) can be a dielectric material having adielectric constant greater than 4.0, 7.0, or 10.0. Non-limitingexamples of suitable materials for the high-k dielectric materialinclude oxides, nitrides, oxynitrides, silicates (e.g., metalsilicates), aluminates, titanates, nitrides, or any combination thereof.Examples of high-k materials include, but are not limited to, metaloxides such as hafnium oxide, hafnium silicon oxide, hafnium siliconoxynitride, lanthanum oxide, lanthanum aluminum oxide, zirconium oxide,zirconium silicon oxide, zirconium silicon oxynitride, tantalum oxide,titanium oxide, barium strontium titanium oxide, barium titanium oxide,strontium titanium oxide, yttrium oxide, aluminum oxide, lead scandiumtantalum oxide, and lead zinc niobate. The high-k material may furtherinclude dopants such as, for example, lanthanum and aluminum.

The high-k dielectric material layer may be formed by known depositionprocesses, for example, chemical vapor deposition (CVD), plasma-enhancedchemical vapor deposition (PECVD), atomic layer deposition (ALD),evaporation, physical vapor deposition (PVD), chemical solutiondeposition, or other like processes.

The work function metal(s) may be disposed over the high-k dielectricmaterial. The type of work function metal(s) depends on the type oftransistor and may differ between the NFET 121 (first transistor) andthe PFET 122 (second transistor). Non-limiting examples of suitable workfunction metals include p-type work function metal materials and n-typework function metal materials. P-type work function materials includecompositions such as ruthenium, palladium, platinum, cobalt, nickel, andconductive metal oxides, or any combination thereof. N-type metalmaterials include compositions such as hafnium, zirconium, titanium,tantalum, aluminum, metal carbides (e.g., hafnium carbide, zirconiumcarbide, titanium carbide, and aluminum carbide), aluminides, or anycombination thereof.

A conductive metal is deposited over the high-k dielectric material(s)and workfunction layer(s) to form the gate stacks of the gates 810, 811.Non-limiting examples of suitable conductive metals include aluminum(Al), platinum (Pt), gold (Au), tungsten (W), titanium (Ti), or anycombination thereof. The conductive metal may be deposited by a knowndeposition process, for example, CVD, PECVD, PVD, plating, thermal ore-beam evaporation, and sputtering. A planarization process, forexample, chemical mechanical planarization (CMP), is performed to polishthe surface of the conductive gate metal.

FIGS. 9-11 illustrate an exemplary method of making a semiconductordevice according to a second embodiment of the present invention. FIG. 9is a cross-sectional side view after etching to remove the p-doped oxide210 (first doped oxide) and the n-doped oxide 410 (second doped oxide)from around the fins 110 of FIG. 5, after annealing to drive in thedopants and form the PTS regions. In contrast to the first embodimentshown in FIG. 6, in which spacers 601, 602, 603 are formed, the p-dopedoxide 210 and p-doped oxide 410 are substantially completely removedwithout forming spacers alongside the doped fin regions 501, 502.

A dry etching process, for example, and RIE process may be used toexpose the pinch off regions 211, 411 between the fin doped regions 501,502, as shown in FIG. 5. An isotropic etching process, for example, awet etching process containing hydrofluoric acid may then be used toremove the remaining p-doped oxide 210 and n-doped oxide 410.

FIG. 10 is a cross-sectional side view after depositing an undoped oxide1001 around and between the fins 110 to form STI regions, recessing theundoped oxide 1001, and removing the spacers 130 and hard mask 111. Theundoped oxide 1001 may include any suitable materials described above inFIG. 7A for the undoped oxide 701. A planarization process, for example,chemical mechanical planarization (CMP), is performed to smooth thesurface of updoped oxide 1001. Following planarization, undoped oxide1001 is recessed and the spacers 130 and hard mask 111 are stripped asdescribed above in FIG. 7B. The undoped oxide 1001 is recessed to aregion that is below the interface 1010 between the doped fin regions501, 502 and the fin channels 510.

FIG. 11 is a cross-sectional side view after forming gates 1110, 1111around the fin channels 510. The gates 1110, 1111 may include gatestacks as described above for gates 810, 811 in FIG. 8.

FIGS. 12-15 illustrate an exemplary method of a making semiconductordevice according to a third embodiment of the present invention. FIG. 12is a cross-sectional side view after etching to recess the p-doped oxide210 (first doped oxide) and the n-doped oxide (second doped oxide) andleave spacers 1201, 1202 around a portion of fins shown in FIG. 4. Theetching process is employed before annealing to drive in the dopants.The etching process may a dry etching process, for example, an RIEprocess.

The spacers 1201, 1202 form along sidewalls of the fins 110 and aresingle layer spacers. The spacer 1201 in the NFET region 120 includesthe p-doped oxide 210. The spacer 1202 in the PFET region 121 includesthe n-doped oxide 410. The spacers 1201, 1202 are formed between thespacers 130 and the substrate 101.

FIG. 13 is a cross-sectional side view after annealing to drive thedopants into the fins 110 and the substrate 101. A thermal annealingprocess may be employed as described above in FIG. 6 to drive the p-typedopants and the n-type dopants of the p-doped oxide 210 and the n-dopedoxide 410, respectively, into the exposed fin regions to form doped finregions 1401, 1402. The dopants are also driven into the substrate 101to from corresponding doped substrate regions 1410, 1411. The doped finregions 1401, 1402 and doped substrate regions 1410, 1411 form the PTSregions.

The doped fin regions 1401, 1402 and doped substrate regions 1410, 1411will be doped with the type of dopant within the overlaying doped oxidelayer. For example, the p-type dopants from the p-doped oxide 210 willbe driven into fins 110 and substrate 101 of the NFET 121. The n-typedopants from the n-doped oxide 410 will be driven into the fins 110 andsubstrate 101 of the PFET 122.

The doped substrate regions 1410, 1411 include a gradient dopantprofile. In contrast to embodiments one and two (see, e.g., FIGS. 5 and9) the doped substrate regions 1410, 1411 are smaller and may bediscrete (compare doped substrate regions 503, 504), which means thatless dopants are in the substrate 101 because the p-doped oxide 210 andn-doped oxide 410 are removed (see FIG. 12) before annealing.

The fin channels 510 are protected by the spacers 130 and remainundoped. The spacers 130 function as a diffusion barrier in the region141 of the fins 110. Thus, the dopants are only driven into the fins 110in the region 140 not protected by the spacers 130.

FIG. 14 is a cross-sectional side view after removing the spacers 1401,1402 and hard mask 111 and depositing an undoped oxide 1403 around thefin channels 510. In some embodiments, the spacers 1401, 1402 are notremoved and the undoped oxide 1403 is deposited over the spacers 1402,1402.

The undoped oxide 1401 may include any suitable materials describedabove in FIG. 7A for the undoped oxide 701. A planarization process, forexample, chemical mechanical planarization (CMP), is performed to smooththe surface of updoped oxide 1401. The undoped oxide 1401 is recessedand the spacers 130 and hard mask 111 are stripped also as describedabove in FIG. 7B.

FIG. 15 is a cross-sectional side view after forming gates 1510, 1511over the fins channels 510. The gates 1510, 1511 may include gate stacksas described above for gates 810, 811 in FIG. 8.

As described above, embodiments of the present invention provide methodsof making semiconductor devices with several advantages. Embodiments ofthe present invention provide methods of making semiconductor deviceswith a dual doped STI liner. The methods only need a single mask forpatterning. The methods do not include etching materials through theentire depth of high aspect ratio STIs. The methods also do not includedepositing a capping layer onto doped oxide. Embodiments of theinventive structure and methods are suitable for highly scaled fin pitchdevices.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, element components,and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

The flow diagrams depicted herein are just one example. There may bemany variations to this diagram or the steps (or operations) describedtherein without departing from the spirit of the invention. Forinstance, the steps may be performed in a differing order or steps maybe added, deleted or modified. All of these variations are considered apart of the claimed invention.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A method of making a semiconductor device, themethod comprising: forming a first fin of a first transistor in asubstrate; forming a second fin of a second transistor in the substrate;disposing a first doped oxide layer comprising a first dopant onto thefirst fin and the second fin, the first dopant being an n-type dopant ora p-type dopant; disposing a mask over the first fin and removing thefirst doped oxide layer from the second fin; removing the mask anddisposing a second doped oxide layer directly onto the first doped oxidelayer covering the first fin and directly onto the second fin, thesecond doped oxide layer comprising an n-type dopant or a p-type dopantthat is different than the first dopant; and annealing to drive in thefirst dopant into a portion of the first fin and the second dopant intoa portion of the second fin.
 2. The method of claim 1, wherein the firstfin and the second fin further comprise a hard mask cap and a sidewallspacer.
 3. The method of claim 1, wherein the first doped oxide layerhas a thickness in a range from about 3 to about 30 nanometers (nm). 4.The method of claim 1, further comprising recessing the first dopedoxide and the second doped oxide to form a doped oxide spacer along aportion of a sidewall of the first fin.
 5. The method of claim 4,wherein the doped oxide spacer comprises a bilayer of the first dopedoxide layer and the second doped oxide layer, the first doped oxidelayer being adjacent to the first fin, and second doped oxide layerforms a single layer spacer disposed onto another portion of thesidewall.
 6. The method of claim 5, wherein recessing the second dopedoxide forms a doped oxide spacer comprising the second doped oxide layeralong a sidewall of the second fin.
 7. The method of claim 6, furthercomprising filling a region between the first and second fins with anundoped oxide.
 8. The method of claim 1, further comprising removing thefirst and second doped oxide layer from around the first and secondfins, and filling a region between the first and second fins with anundoped oxide.
 9. The method of claim 1, wherein the first or secondtransistor further comprise a third fin adjacent to the first or secondfin, and the first doped oxide layer or the second doped oxide layerpinches off between the third fin and either the first or second fin.10. A method of making a semiconductor device, the method comprising:forming a first fin of a first transistor in a substrate, the first finhaving a hard mask arranged on a surface of the first fin and spacersarranged on sidewalls of the first fin; forming a second fin of a secondtransistor in the substrate, the second fin having a hard mask arrangedon a surface of the second fin and a spacer arranged on a sidewall ofthe second fin; removing a portion of the substrate around the first finto extend a height of the first fin and form a gap between the spacer onthe sidewall of the first fin and the substrate; removing a portion ofthe substrate around the second fin to extend a height of the second finand form a gap between the spacer on the sidewall of the second fin andthe substrate; disposing a first doped oxide layer comprising a firstdopant onto the first fin and the second fin such that the first dopedoxide layer is arranged within the gap between the spacer and thesubstrate of the first fin and within the gap between the spacer and thesubstrate of the second fin, the first dopant being an n-type dopant ora p-type dopant; disposing a mask over the first fin and removing thefirst doped oxide layer from the second fin; removing the mask anddisposing a second doped oxide layer directly onto the first doped oxidelayer over the first fin and directly onto the second fin such that thesecond doped oxide layer is arranged within the gap between the spacerand the substrate of the second fin, the second doped oxide layercomprising an n-type dopant or a p-type dopant that is different thanthe first dopant; recessing the first doped oxide and the second dopedoxide to form a first doped oxide spacer along a sidewall of the firstfin and a second doped oxide spacer along a sidewall of the second fin;and annealing to drive in the first dopant into a portion of the firstfin and the second dopant into a portion of the second fin.
 11. Themethod of claim 10, wherein the first doped oxide spacer comprises thefirst doped oxide layer, and the second doped oxide spacer comprises thesecond doped oxide layer.
 12. The method of claim 10, wherein annealingdrives the first dopant and the second dopant into the substrate to formdoped substrate regions.
 13. The method of claim 10, wherein the firstor second fin further comprises a sidewall spacer adjacent to a finchannel region that prevents diffusion of the first or second dopantinto the fin channel region.
 14. The method of claim 10, furthercomprising disposing an undoped oxide between the first and second finsafter annealing.
 15. The method of claim 10, further comprisingdisposing an undoped oxide between the first and second fins beforeannealing.